Formers are rigid molds sized and shaped to define the dimensions of the finished products. Formers are employed in the manufacture of latex and synthetic polymer products, such as examination and surgical gloves and condoms. The formers are typically made of wood, ceramic, glass, porcelain, plastic, steel or aluminum and are dipped, usually fingers first in the case of a glove former, into a liquid latex bath, including admixed chemicals, where the latex adheres to the former. The glove or condom formers may be heated prior to beginning the dipping process. Glove and condom formers are usually pre-coated with a coagulant to gel the latex and to facilitate removal of the article from the former. Typical coagulants include calcium nitrate. Additional dips in latex baths that contain fillers may also be required. The latex is coagulated and the glove or condom is released from the former usually by peeling the glove or condom from the former. The articles may be removed from the former in water. The gloves or condoms may also go through leaching and washing cycles to remove residual chemicals before being stripped from the former. The finished articles are then removed from the former such that the outer layer from the former will be the innermost layer of the glove or condom. The articles may then be packaged and sterilized for shipping.
After repeated cycles of chemical dips, formers begin to degrade and must be replaced. As a benchmark for durability, porcelain formers remain in good condition for up to two weeks when exposed to a concentrated solution of potassium hydroxide.
Ternary ceramics are generally known to be hard or brittle and not suitable for use in the manufacture of machined parts. However, titanium silicon carbide Ti3SiC2 has been synthesized to result in a soft, machinable, strong and lightweight material. Ti3SiC2 is anomalously soft for carbide materials. Single-phase samples of the material were characterized for thermal stability and oxidation-resistance. Sample bars of Ti3SiC2 material were quenched in a pail of water from 1,400° C. and found to have a slightly increased strength after quenching. Samples of Ti3SiC2 materials are also surprisingly machinable. Ceramics are typically too brittle to be machined, however, after drilling through the initial hard crust of the Ti3SiC2 the samples were found to be nearly as machinable as graphite.
Ti3SiC2 has properties of both metals and ceramics. Like a metal, it is machinable, thermally and electrically conductive, resistant to thermal shock and plastic at elevated temperatures. Like a ceramic, it is refractory (i.e., has a decomposition temperature of greater than 2,000° C.), oxidation-resistant, stiff and lightweight (roughly 4.5 grams per cubic centimeter), its thermal expansion is relatively low, more like a ceramic than a metal.
In slip casting, sometimes called drain casting, a plaster of Paris mold is filled with a slip. Slip is a liquid containing a ceramic material in a water suspension. As the mold absorbs water, the ceramic suspension solidifies uniformly on the walls of the mold. Once the desired wall thickness is reached, the remaining slip is drained, the mold is separated or broken, and the part is removed. The part is then sintered in an oven.
WO 98/22244 describes a dense ceramic work piece made by pressing a combination of powdered Ti3SiC2 and a powdered material that is soluble in the Ti3SiC2 into a green body. The green body is then heated under pressureless sintering conditions to a temperature above a point at which a liquid is formed but below the melting point of the mixture. WO 98/22244 does not teach or disclose making hollow objects (like formers) with a plaster of Paris mold and a liquid dispersion of powdered Ti3SiC2.
Conventional formers that are typically made of wood, ceramic, glass, porcelain, plastic, steel or aluminum deteriorate after continual exposure to the heat and chemicals employed during the glove and condom making process. Deterioration causes pitting in the formers, and the gloves and condoms produced from the pitted formers have pin hole sized defects. There is a need, therefore, for glove and condom formers of a durable material that will reduce the frequency with which the formers must be replaced. It is desirable that the durable formers do not otherwise interfere with the quality of the glove or condom produced.